Many incels dont tbh. It's a stereotype. Ugly people "look" dirty due to being repulsive to look at, so are considered to be dirty anyway. Infact many incels clearly are dead set on maintaining hygiene due to it being so common an advice to follow. Meanwhile i'm sure i've seen things before showing that a good number of women regularly go several days without showering or bathing. And fuck, look at all the posts online where girls are complaining about their good looking boyfriends leaving shit stains on the sheets and being unhygienic in general. Yet they stay with them. Countless unhygienic people still succeed. It's just nitpicking at this point.
The issue with normie advice is that its designed to fail, its designed in such a way that when you follow it to a T, they will just call it the bare minimum (which yes hygiene is, unless youre hot), or attack you for "doing it wrong". They will often suggest you do the opposite of what they suggested before, and run you around in circles. Moving the goalposts every time. Every detail, whether its a result of advice followed, will be criticized.
I do recall seeing a post on here years ago, that while odd focus for many due to mainly just focusing on genitalia alone, was actually fairly noteworthy. I cant quote it from memory but it was something akin to - an ugly man can have a hygienic, and well groomed penis, and people will still consider it to be a small, dirty, germ ridden, foul smelling PP.
A hot guy has a dick, he can not shower for a few days, have it be poorly groomed. and have sweat built up, the bodily fluids of a previous woman on it and will still find someone willing to suck it clean.